Sound producing system



Nov. 17, 1964 KAZUKIYO ISHIMURA SOUND PRODUCING SYSTEM 2 Sheets-Sheet 1 Filed Apxfil 25, 1962 Nov. 17, 1964 KAZUKIYO ISHIMURA,

SOUND PRODUCING SYSTEM Filed April 25, 1962 2 Sheets-Sheet 2 7/7172 (sec) United States Patent 3,157,247 SQUND PRGDUfIlNG SYSTEM Kazukiyo lshimura, Shizuolra-ken, Japan, assignor to Nippon Gakki Seize Kahushiki Kaisha, Shizuoka-ken, Japan, a corporation of Japan Filed Apr. 25, 1962, Ser. No. 190,133 4 Claims. (@l. 181--27) This invention relates to sound reproducing "apparatus.

In electronic musical instruments for producing tremolo, vibrato etc. an electronic system has been hitherto used. By means of. an amplitude modulation or a frequency modulation of a sound source with an alternate current power source in the order of l0 c./s., a tremolo, or vibrato is produced. When a sound accompanied by tremolo or vibrato as produced by such means is reproduced by a plurality of speakers, the sound has the same effect as if it is played with but a single musical instrument. However, in musical instruments in general, especially in string instruments there are substantial differences between the performance with one musical instrument and a plurality of musical instruments, not only in the increase of sound volume but in the production of a concert effect. This is because of the differences of pitch and phase of each instrument. When the performance is accompanied with a vibrato or tremolo the differences in phase and depth emphasize the so called concert effect and enlar e the sound range, resultin in a lively performance.

In order to obtain a concert effect with but a single electronic musical instrument, the sonic function of said instrument is to be doubled, which is impossible by the conventional electronic manner of obtaining tremolo or vibrato. The object of this invention is to produce such a concert effect with one electronic musical instrument.

In order that the said invention may be clearly understood and readily carried into effect the same will be hereinafter more fully described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a speaker cabinet in which the device according to this invention is assembled;

FIG. 2 is a partially fragmented side view of the device of this invention;

FIG. 3 is a partial plan view of FIG. 2 taken on the line 33;

FIGS. 4a and 4-19 illustrate separate embodiments of devices for attaching the speakers within the cabinet;

FIG. 5 is a longitudinal sectional view showing the attachment of a reflecting plate;

FIGS. 6a and 6b are perspective views of two separate embodiments of reflecting plates;

FIG. 7 is a diagram showing the electrical connections of the speakers of the device of the invention;

FIG. 8 illustrates the wave form of the sound produced from the speaker.

In FIG. 1 the device of the present invention is assembled in a speaker cabinet 1 which is provided with outlets 2 and 3 for the sound produced from the speakers. In FIG. 2, as is well known, the Woofer 5 is fixed in the front portion of cabinet 1 and the high frequency reproducing speakers or tweeters are each supported by L- shaped elements 8 which are affixed on a shelf plate 4 horizontally attached in the upper portion of cabinet 1. The tweeters 6 surround the rotary sound reflecting plate 7, which is alfixed on rotary shaft 18 which is vertically supported by a bearing 9 supported in shelf plate 4. The tweeters 6 are disposed regularly on the shelf plate 4 around the reflecting plate as a center. A pulley 13 is rigidly connected to the rotary shaft 18 and the rotary reflecting plate 7 so as to drive the latter from a motor 10 through a belt 11. The diameter of pulley 13 determines the ratio of the number of revolutions of the motor to that of the reflecting plate. FIG. 3 shows five speakers 6 disposed on shelf plate 4 facing inwardly to wards the reflecting plate 7. The said reflecting plate 7 is driven at the center of the arranged speakers 6 by motor 10 through the medium of belt 11. The reflecting plate is rotated at between 300600 rpm. FIG. 7 is the connection diagram of the speakers of the device of the invention. Numeral 19 designates the source of electronic musical tone signals. Signals produced from source 19 are amplified by amplifier 12 and impressed upon Woofer speaker is with the plurality of speakers 6 connected in parallel. It is evidently needless to mention that speakers 6 may be connected in series with woofer 5 or in a seriesparallel arrangement. Numeral 2t) designates a low frequency rejection filter; 15 designates the signal line from speakers 6; and 17 designates an input terminal provided in casing is for speakers 6.

The sounds produced from the plurality of speakers 6 used in this invention are all of identical phase. This refers to the connections of the plurality of speakers 6 irrespective of the reflecting plate. When reflecting plate 7 begins to rotate however, the sound range of the sound emanating from the speakers 6 changes in proportion to the revolution of reflecting plate as shown in FIG. 8 in which the horizontal axis shows time, and the vertical axis shows sound pressure. Namely the sound is subjected to amplitude modulation so that the effect of tremolo is produced. in this case the phases of the individual amplitude modulation of the speakers 6 are not identical as shown in FIGS. 8ae. When all speakers 6 are disposed on the same circumference, the magnitude of amplitude from the speakers are identical. When they are disposed at different distances from the reflecting plate, the depth of amplitude becomes shallow. In other words when the speakers are individually disposed at different radii from the reflecting plate, the phase and depth of tremolos of the sounds coming from each speaker are distinguished one from the other. Since the sound emanating from the back of speakers 6 decreases the effect of tremolo, the speakers s are covered by cover 14 made of polyurethane foam felt or the like, as shown in FIG. 4-11. Alternately as shown in FIG. 4b, speaker 6 may be covered by casing 17 instead of cover 14 so as to absorb the sound emanating from the back of the speakers. The sound coming from the front of speaker 6 is reflected by rotating reflecting plate 7. The sound reflecting plate 7 extends radially in opposite direction from axle 13 towards the speakers. As the plate 7 rotates, the sound from the speakers s is irregularly reflected, causing directivity of the sound to be improved and the effect of tremolo to become smooth. As to the shape of the plate, it is preferred to employ, a conical reflecting plate 7b, on a centering shaft 18 of small diameter, with gradually outward increasing diameters and circular terminal ends 71) as shown in FIG. 6-b, however, it is also possible to utilize the tapered flat reflecting plate 7a, having rectangular terminal ends 7:: as shown in FIG. 6a. The circular terminal ends 7]) of the conical plate have a diameter which is approximately equal to the diameter of the speakers 6 as shown in FIG. 3. Since the plurality of speakers 6 emphasize the concert effect particularly in the middle tonal range, mid-range speakers are advisable. Since it is structurally difficult to dispose around the reflecting plate, a plurality of speakers for reproducing low frequencies, it is preferred to provide a separate woofer as shown in FIG. 2 or 7.

By attaching the device of this invention to an electronic musical instrument one can easily produce a concert eflect which has never been acquired with a single electronic musical instrument. Moreover this invention can be applied not only to electronic musical instruments but to musical instruments in general. Namely by amplifying with an amplifier attached to the device of this invention, one can produce the effect of performance with several musical instruments.

1 claim:

1. A sound producing system comprising a sound reflector adapted for rotating about an axis, and a plurality of speakers arranged around said reflector in spaced relation and facing inwardly towards said reflector, said reflector including a radial element extending from said axis towards said speakers and including a terminal end which successively faces the speakers as said reflector rotates about said axis, said reflector being a flat plate and said terminal end having a rectangular shape.

2. A sound producing system comprising a sound reflector adapted for rotating about an axis, and a plurality of speakers arranged around said reflector in spaced relation and facing inwardly towards said reflector, said refiector including a radial element extending from said axis towards said speakers and including a terminal end which successively faces the speakers as said reflector rotates about said axis, said radial element of said reflector being of conical shape with increasing diameters in a direction radially outwards from said axis.

3. A sound system as claimed in claim 2 wherein said speakers are of the same diameter and the diameter of said radial element at said terminal end is approximately equal to the diameter of the speakers.

4. A sound producing system comprising a sound reflector adapted for rotating about an axis, and a plurality of speakers arranged around said reflector in spaced relation and facing inwardly towards said reflector, said reflector being a flat plate including two radial elements extending from said axis towards said speakers and including terminal ends which successively face the speakers as said reflector rotates about said axis, said elements extending in a common plane in opposite direction in increasing tapered fashion radially outwards from said axis.

References tCited in the file of this patent UNITED STATES PATENTS 2,062,515 Hoschke Dec. 1, 1936 2,114,680 Goldsmith Apr. 19, 1938 2,450,139 Hartsough Sept. 28, 1948 2,489,653 Leslie Nov. 29, 1949 2,780,302 George Feb. 5, 1957 2,869,667 Leslie Ian. 20, 1959 3,069,958 Arsem et al Dec. 25, 1962 3,095,940 Santi July 2, 1963 

1. A SOUND PRODUCING SYSTEM COMPRISING A SOUND REFLECTOR ADAPTED FOR ROTATING ABOUT AN AXIS, AND A PLURALITY OF SPEAKERS ARRANGED AROUND SAID REFLECTOR IN SPACED RELATION AND FACING INWARDLY TOWARDS SAID REFLECTOR IN SPACED RELAFLECTOR INCLUDING A RADIAL ELEMENT EXTENDING FROM SAID AXIS TOWARDS SAID SPEAKERS AND INCLUDING A TERMINAL END WHICH SUCCESSIVELY FACES THE SPEAKERS AS SAID REFLECTOR ROTATES ABOUT SAID AXIS, SAID REFLECTOR BEING A FLAT PLATE AND SAID TERMINAL END HAVING A RECTANGULAR SHAPE. 